1. Field of the Invention
This invention relates to a semiconductor device having a structure in which a plurality of semiconductor chips is stacked and a specific semiconductor chip can be selected, and particularly relates to a semiconductor device in which a unique identification number is assigned to each semiconductor chip in order to select a specific semiconductor chip.
2. Description of the Related Art
Recently, an increase in storage capacity is required for semiconductor memories such as DRAMs. Construction of the semiconductor memory using a single semiconductor chip requires finer microfabrication and the yield deteriorates. Therefore, a stacked type semiconductor device having a structure in which a plurality of semiconductor chips is stacked has been proposed. For example, by employing a 3 dimensional structure in which a plurality of semiconductor chips of the same type is stacked in multiple layers, a small stacked type semiconductor device having a large storage capacity can be realized, which can be controlled from outside in the same manner as a single DRAM.
When using such a stacked type semiconductor memory device, means for identifying each of semiconductor chips to selectively operate a specific semiconductor chip is required. Therefore, a structure is proposed, in which connection paths for selection signals applied to the semiconductor chips are formed by connecting electrodes of every semiconductor chip in the stacking order and a different selection signal is applied to each semiconductor chip through each connection path formed separately from each other so as to select a specific semiconductor chip (for example, JP-A-2002-305283). However, in such a structure, it is necessary to separately form the connection paths for the selection signals, the number of which is the same as that of stacked layers, and thus when stacking a large number of semiconductor chips, the complicated stacked structure having a large number of electrodes is needed and the production cost increases. Meanwhile, a stacked type semiconductor device is proposed, in which chip identification numbers are individually assigned to a plurality of semiconductor chips and a semiconductor chip having the identification number equal to the selection signal can be selected by assigning the chip identification numbers to the plurality of semiconductor chips individually in order to prevent the electrodes from increasing even when increasing the number of stacked layers (for example, JP-A-2003-110086). In such a stacked type semiconductor device, the connection paths can be shared among the plurality of semiconductor chips. For example, by forming N connection paths, one of 2N semiconductor chips can be selected and thereby simplifying the electrode structure.